Evothings Client is based on Cordova and bluetoothserial is Cordova's plugin. Evothings has everything you need for this tutorial. Just follow from Step 1 to Step 5. In Step 5, you will be asked to download Evothings Studio and also example app code from my github repository. Just follow the instructions given in this step.Once you have the app working, you can then read from Step 6 to Step 8 to develop further understanding of how example app code is working.About the reply to kvascian, that part comes once you have completed your app and now want to publish the app to Android or iOS app stores.